OLED Display Panel Contact Structure for Circuit Reliability
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Solution Overview
Problem
In OLED display panels, the high sheet resistance of thin transparent cathodes leads to voltage drop and non-uniform luminance, causing a risk of broken circuits during cell-assembling due to excessive pressure between the auxiliary electrode and the cathode.
Innovation Solution
A contact structure is introduced between the cathode and the auxiliary electrode, featuring a spacer and transparent conductive film on the color filter substrate, with a depressed section on the array substrate to increase the contacting area and reduce pressure, and optionally using conducting glue to ensure electrical connection and prevent resistance issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a thin transparent cathode is used to increase light transmittance, then light transmittance is improved, but sheet resistance increases causing voltage drop and non-uniform luminance
Solution Approach 1:
An auxiliary electrode is introduced as an intermediary component between the transparent cathode and the power supply. This auxiliary electrode has lower sheet resistance than the transparent cathode, allowing it to serve as an intermediate conductor that supplies power more uniformly across the display panel while maintaining the light transmittance benefits of the thin transparent cathode.
Solution Approach 2:
The power supply function is segmented into two parts: the transparent cathode maintains light transmittance while the auxiliary electrode provides low-resistance power distribution. This segmentation allows each component to optimize its specific function without compromising the other.
2Reliability
If excessive pressure is applied between the auxiliary electrode and the cathode during cell-assembling, then electrical connection is improved, but the risk of broken circuit increases
Solution Approach 1:
A spacer is introduced as a cushioning element between the auxiliary electrode and the cathode. This spacer provides mechanical support and distributes the pressing force uniformly during cell assembly, preventing excessive localized pressure that could break the circuit while still ensuring adequate electrical contact through the transparent conductive film.
Solution Approach 2:
A transparent conductive film is used to cover the auxiliary electrode, providing a flexible conducting layer that can conform to the spacer structure. This thin film maintains electrical conductivity while accommodating the mechanical constraints imposed by the spacer during assembly.
3Reliability
If the contacting area between the auxiliary electrode and the cathode is increased to reduce pressure, then the risk of broken circuit is reduced, but the device structure becomes more complex
Solution Approach 1:
The contacting area is increased by utilizing the vertical dimension through the spacer height rather than only expanding the horizontal area. The spacer creates a stepped structure where the transparent conductive film contacts the cathode over a larger effective area without significantly increasing the planar footprint of the device.
Data Source
AI summary
Disclosed are an OLED display panel and an OLED display device. The OLED display panel includes an array substrate (21) which is covered by a cathode (211) and a color filter substrate (22) on which an auxiliary electrode (221) is formed. A contact structure is disposed between the color filter substrate (22) and the array substrate (21) to electrically connect the cathode (211) and the auxiliary electrode (221), and the contacting area between the contact structure and the array substrate (21) is greater than or equal to that between auxiliary electrode (221) and the contact structure. The OLED display panel avoids broken circuit between the auxiliary electrode and the cathode that tends to occur due to excessive pressure upon cell-assembling a top-emitting OLED display panel.